I have co-organized 3 Meetings on Statistical Mechanics at Camerino and a
Workshop on Granular System in Pisa in 1998.
I also coorganized the Conferenza Nazionale di Meccanica Statistica di Parma
Italy from 1993 to 1997.

Member of the Scientific Committee of the INFM Conference
held in Fai della Paganella and now in Levico Terme.

The last few years have seen an extraordinary growth of interest in
complex systems. From physics to biology, from economics
to cognitive sciences, a new vocabulary is emerging to describe
discoveries about wide-ranging and fundamental phenomena.

Statistical Mechanics has become in the last decades the standard tool
to study problems once considered to be out of the reach
and the scopes of Physics.
It has been in fact applied to the study of the complex behavior of
various kinds of systems of areas such as biological and sociological
sciences, finance, economy, theory of decisions, networks.
In particular several disciplines connected with Engineering are now
attracting more and more the interest of physicsts.
Granular matter is a remarkable example of these new disciplines.
The problem of understanding granular materials is widely recognized
as one of the main problems of engineering and industry. A
brief list of typical "granular" products comprehends: grains,
powders, sands, pills, seeds and similar particulate materials. More
generally, granular materials are a very large set of substances used
in the industry and in the everyday life: ceramics, fertilizers,
cosmetics, food products, paper, conductor pastes, resins,
electronics, polymers, suspensions, solid chemicals, construction
materials and so on. The international economic impact of particle
processing is substantial. The value added by manufacture that
involves particulate has been estimated to be a minimum of 80/100
billion/year, which is of the order of the US trade deficit with
Japan. The US Dept. of Commerce has estimated the total economic
impact of particulate products to be one trillion/year. Despite
economic impact, however, insufficient attention is paid to
difficulties associated with the processing of particles. An improved
understanding of micromechanics of granular media requires an
interdisciplinary approach involving both physicists and
engineers.

Mechanical engineers and geologists have studied Granular Matter for at least
two centuries and found several empirical laws describing its behavior.
Physicists have joined in more recently and
are interested in formulating general laws. For them granular matter is
a new type of condensed matter, showing two states: one fluid-like,
one solid-like. But there is not yet consensus on the description of these
two states. According to P.G. de Gennes Granular matter now is at the level
of solid-state physics in 1930.

Granular matter also represents an important paradigm for the study of
non-equilibrium stationary states. Due to the dissipative nature of the
interactions granular gases have to be considered as open systems
and therefore concepts from equilibrium thermodynamics cannot be applied,
at least in straightforward way.
The project we propose focuses on granular fluids.
We intend by granular fluid a large number of particles, whose
size is larger than a micron, colliding
with one another and losing a little energy in each collision.
Below one micron thermal agitation is important and Brownian motion
can be observed. Above one micron, thermal agitation is negligible.
However,if such a system is shaken to keep it in motion,
its dynamics resembles that of fluids, in that the grains move randomly.

One of the key differences between a granular material and a regular
fluid is that the grains of the former lose energy with each
collision, while the molecules of the latter do not. Even when the
inelasticity of the collisions is small, it can give rise to dramatic
effects, including the Maxwell Demon effect and
the phenomenon of granular clustering. Experiments and molecular dynamics
simulations alike show that granular gases in the
absence of gravity do not become homogeneous with time, but instead
form dense clusters of stationary particles surrounded by a lower
density region of more energetic particles. From a particulate point
of view, one can explain these clusters by noting that when a particle
enters a region of slightly higher density, it has more collisions,
loses more energy, and so is less able to leave that region, thus
increasing the local density and making it more likely for the next
particle to be captured.